1. Field of the Invention
Embodiments of the invention generally relate to moisture curable compositions including silylated polymers and methods for producing the same.
2. Description of the Related Art
Polyurethane (PU) prepolymers have been widely used in adhesive and sealant applications owing to their superior performances and relatively low cost. In recent decades, however, isocyanate-containing polyurethane prepolymers have faced increasing environmental regulation due to the presence of free isocyanates. As a result, for many applications, conventional polyurethane prepolymers have now been replaced with isocyanate-free alternatives, for example, silylated polymers.
Silylated polymers or crosslinkable silane-terminated polymers (STPs) are widely used as raw material polymers in coating materials, adhesives, sealing materials, elastomers and the like (CASE applications) for architectural or industrial use. Silylated polymers typically comprise polyether polyols and reactive alkoxysilane end groups. Depending on end-use applications, the mechanical property requirements of a cured silylated polymer varies significantly.
Although silylated polymers offer many advantages over polyurethane prepolymers, opportunities for improvement exist. One such opportunity involves the reduction of compression set in cross-linked or cured silylated polymers. Compression set is a measure of the deformation of a polymer after it has been exposed to compressive stress under controlled time and temperature conditions. Compared to cross-linked or cured polymers made from polyurethane prepolymers cross-linked or cured polymers made from silylated polymers were found to have high compression set, which prevents the products from being used under cyclic/dynamic loads, such as gaskets and sealing rings. For parts made from silylated polymers used in applications exposed to long term continuous load or infrequent load/unload cycles, product durability is of concern.
Therefore, there is a need for cross-linked or cured silylated polymers and compositions having cross-linked or cured silylated polymers exhibiting improved compression set properties.